To understand the immune response to Francisella tularensis {Ft), and its interaction with immune cells, histological and immunohistochemical analysis of cells and tissues, as well as an analysis of individual immune cell populations and signaling molecules produced, is required. Thus, the purpose of Core C is to provide the means and technological expertise for investigators to analyze immune cells, quantify signalling molecules (cytokines and intracellular signaling molecules), and histologically identify cells and tissues obtained from mice. This includes the use of immunohistochemical techniques to localize and identify antigens on the surface of, and inside immune cells. This Core facilitv will be composed of three primarv components: (1) A Flow Cytometry service. (2) A Cytometric Bead Array (CBA) Protein Detection service, and (3) A Histochemistrv/lmmunohistochemistry service. All three services are currently available, and being provided to P01 investigators on all 4 currently funded subprojects. In regard to the current proposal. Core C will continue to provide the above services to POI investigators on all 3 currently proposed subprojects. The function of the three Immunology Core components is indicated in more detail below: 1. Flow Cytometry Service: This component will provide investigators access to flow cytometry analysis and cell sorting for the purpose of analyzing individual immune cell populations, including surface marker expression and intracellular cytokine production. Specific functions will include: fPlow cytometer operation, investigator training, equipment maintainance, ordering of reagents and supplies; 2. CBA Protein Detection Service This component will utilize an established CBA technology developed by Becton Dickinson to quantitate secreted cytokines and intracellular signalling molecules utilizing a FACSArray flow cytometer dedicated to this purpose. Specific functions will include: acquiring reagents and kits, performing assays, performing flow cytometric analyses of samples, assisting in data/assay interpretation when appropriate, and maintaining required equipment; 3. Histology/lmmunohistochemistry Service: This component will process cells and tissues provided by investigators for histologic and immunhistochemical evaluation. Functions will include tissue embedding and sectioning, histochemical and immunohistochemical staining of cells and tissues, equipment maintainance, and assistance in the data interpretation; Core C will now also produce, test, and standardize inactivated Ff-mAb complexes, which will be used by all 3 subprojects. RELEVANCE (See instmctions): To understand the immune response to Francisella tularensis, and its interaction with immune cells, histological and immunohistochemical analysis of cells and tissues, as well as an analysis of individual immune cell populations and signaling molecules produced, is required. Core C will provide the means and technological expertise for investigators to analyze immune cells, quantify signalling molecules (cytokines and intracellular signaling molecules), and to histologically identify cells and tissues obtained from mice.